This section includes a full range of different HID (High Intensity Discharge) bulbs. All of these bulbs carry a one year guarantee as long as the original packaging is kept to offer you piece of mind. As a general rule, Metal Halide (MH) bulbs emit a more blue spectrum of light which is generally suitable for plants in vegetative growth, whilst High Pressure Sodium (HPS) bulbs emit a red/orange spectrum and is more suitable for plants that are flowering.